Chuck Norcutt wrote:
> I had not read this before and you raise some interesting and perplexing
> questions. I knew they were using DXO something and, since they show
> resolution in excess of the sensor resolution, I had assumed (bad) that they
> were measuring the lens independent of the sensor and also with the sensor
> since the tests clearly use a particular camera. You are right... where does
> the lens resolution beyond the sensor Nyquist limit come from?
>
"Whenever the measured numbers exceed this value, this simply indicates
that the lens out-resolves the sensor at this point - the calculated MTF
values themselves become meaningless." Meaningless, but published.
BTW, I really don't mean to slag their lens tests. I think they are
valuable and useful. I suspect that the things they measure are probably
fairly useful analogs for the more subtle things, i.e. those that do
well mostly will do well in less tangible areas of performance.
Hard too, to fault them for not measuring the unmeasurable. :-)
Given the paucity of useful tests of lenses on FF sensors, I think they
are a great service. The side-by-side comparison feature is great. In a
short time, I can see just how the 50/1.8 I have compares to the 50/1.4
in the areas they measure. At f1.8, the faster lens fall below the
slower one, and performance at f1.4 is well below the standard of both
lenses from f2.0-11.
It looks too, like the f1.8 might theoretically be easier to focus
manually, as it is significantly sharper wide open than is the f1.4.
That doesn't factor in differences in MF focusing mechanisms. In any
case, I can see that upgrading would be about build quality, a tiny bit
of speed, AF speed/noise and bokeh, not sharpness, contrast and distortion.
Moose
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